The localized multicast approach reduces expended network resources by limiting transmissions to a geographic area defined by the radio coverage area of a base transceiver station or even smaller areas as defined by antenna coverage sectors of the base transceiver station. Multicast services in general are described in various standards such as the Third Generation Partnership Project (3GPP), Universal Mobile Telephone System (UMTS) standards.
Localized multicast is likewise generally described in the UMTS standards. The UMTS standards, Release 6, define a counting procedure for Multimedia Broadcast, Multicast Service (MBMS) whereby the network learns the status of mobile devices in each cell and configures Radio Bearers (RBs) based upon the learned status information.
Two modes of operation are employed in the standards, namely, Point-to-Point (PTP) and Point-to-Multipoint (PTM). Under counting procedures, coverage areas having less than a preset number of users, employ PTP operation which requires setup of RBs individually per user. Conversely, coverage areas having at least the preset number of users will employ PTM for MBMS delivery wherein individual RBs are not required.
These known procedures for MBMS delivery, more specifically, the procedures for selecting/switching between PTP and PTM modes have several disadvantages. First, employing and switching between two transmission modes complicates network procedures such as, but not limited to, Radio Link Control (RLC) buffer management, RB switching, etc.
Second, using PTP fails to take advantage of the performance gain that may be achieved through using macro-diversity with PTM.
Third, PTP/PTM switching requires a certain degree of counting accuracy which can cause undesired network loading on both the uplink access channel and the Radio Network Controller (RNC).